Arizona prosecutors pressing the case against Republicans who are accused of trying to overturn the 2020 election results in President Donald Trump’s favor were dealt a setback when a judge ordered the case be sent back to a grand jury.

Arizona’s fake elector case remains alive after Friday’s ruling by Maricopa County Superior Court Judge Sam Myers, but it’s being sent back to the grand jurors to determine whether there’s probable cause that the defendants committed the crimes.

The decision, first reported by the Washington Post, centered on the Electoral Count Act, a law that governs the certification of a presidential contest and was part of the defendants’ claims they were acting lawfully.

While the law was discussed when the case was presented to the grand jury and the panel asked a witness about the law’s requirements, prosecutors didn’t show the statute’s language to the grand jury, Myers wrote. The judge said a prosecutor has a duty to tell grand jurors all the applicable law and concluded the defendants were denied “a substantial procedural right as guaranteed by Arizona law.”

Richie Taylor, a spokesperson for Arizona Attorney General Kris Mayes, a Democrat whose office is pressing the case in court, said in a statement that prosecutors will appeal the decision. “We vehemently disagree with the court,” Taylor said.

Mel McDonald, a former county judge in metro Phoenix and former U.S. Attorney for Arizona, said courts send cases back to grand juries when prosecutors present misleading or incomplete evidence or didn’t properly instruct panel members on the law.

“They get granted at times. It’s not often,” said McDonald, who isn’t involved in the case.

In all, 18 Republicans were charged with forgery, fraud and conspiracy. The defendants consist of 11 Republicans who submitted a document falsely claiming Trump won Arizona, two former Trump aides and five lawyers connected to the former president, including Rudy Giuliani.

Two defendants have already resolved their cases, while the others have pleaded not guilty to the charges. Trump wasn’t charged in Arizona, but the indictment refers to him as an unindicted coconspirator.

Most of the defendants in the case also are trying to get a court to dismiss their charges under an Arizona law that bars using baseless legal actions in a bid to silence critics.

They argued Mayes tried to use the charges to silence them for their constitutionally protected speech about the 2020 election and actions taken in response to the race’s outcome. Prosecutors said the defendants didn’t have evidence to back up their retaliation claim and that they crossed the line from protected speech to fraud.

Eleven people who had been nominated to be Arizona’s Republican electors met in Phoenix on Dec. 14, 2020, to sign a certificate saying they were “duly elected and qualified” electors and claimed Trump had carried the state in the 2020 election.

President Joe Biden won Arizona by 10,457 votes. A one-minute video of the signing ceremony was posted on social media by the Arizona Republican Party at the time. The document later was sent to Congress and the National Archives, where it was ignored.

Prosecutors in Michigan, Nevada, Georgia and Wisconsin have also filed criminal charges related to the fake electors scheme.